Most big companies have moved to speech recognition for their phone systems, but that doesn't mean old-fashioned button pushing is dead. Here are some rules of thumb I've developed about when it's a good idea to use DTMF (aka Touch-Tone) in a speech system:
- If you're asking the customer to input a bunch of numbers (i.e. credit card number, order number, account number, etc.) you should ALWAYS allow DTMF input. A substantial percentage of callers will try to dial the number even if you tell them to speak it. Plus it works better.
- "Press or say one" style application design should be avoided--it has the expense of speech with none of the advantages.
- Whenever possible, speech prompts should allow a DTMF fallback. There will always be situations where speech doesn't work, but you don't need to tell the caller about the DTMF option unless there's an error. For example, start with "Do you want sales, customer service, or technical support?" to prompt a spoken response, but if that fails, offer "What department do you want? You can say the name of the department or press one for sales, two for customer service, or three for technical support."
- For the love of all that is beautiful and innocent in this world, please don't disable the "zero" option to reach a live person! It doesn't work, and is the most effective way to really make your customers mad.